The present invention is directed to a metal-gas battery with a cathode comprising nitric oxide (NO) as an active material wherein the nitric oxide may be supplied in the form of an exhaust stream from a combustion process.
In prior U.S. application Ser. No. 14/150,168, a metal-nitric oxide battery was described. The metal-nitric oxide battery is of great interest due to properties such as 1) a high redox potential at 1.0 V. vs. Ag/Ag+; 2) high reversibility; and 3) negligible influence of the supporting electrolyte salt on the NO redox reaction in comparison to a metal-O2 gas battery. In one embodiment described in the previous application, exhaust gas from a combustion engine was collected in a NO absorber which served as a supply source of NO for the battery.
Nitric oxide is known to undergo oxidation to higher nitrogen oxides such as NO2 and N2O4 in the presence of H2O and O2, both of which are components of a combustion exhaust stream. Moreover, such an exhaust stream will also contain hydrocarbons and carbon monoxide.
Purification of the exhaust gas containing NO produced by combustion of a fossil fuel such as gasoline may be contemplated in order to maximize efficiency of a metal-nitric oxide battery system. However, the inventors have recognized that the technology required for isolation and purification of the NO would add cost and equipment to the system. Therefore, in order to increase the potential efficiency and utility of the metal-nitric oxide battery system there is a need to identify and develop a battery capable of functioning with an NO feed which is an exhaust gas composition containing nitric oxide.